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Ride Sharing App FTA Study
Last registered on November 23, 2020


Trial Information
General Information
Ride Sharing App FTA Study
Initial registration date
November 12, 2020
Last updated
November 23, 2020 12:47 PM EST

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Primary Investigator
the Access to Justice Lab at Harvard Law School
Other Primary Investigator(s)
PI Affiliation
the Access to Justice Lab at Harvard Law School
Additional Trial Information
In development
Start date
End date
Secondary IDs
Failure to appear (FTA) in a criminal court case is costly for both the State and the defendant. Research shows defendants miss their court hearings for numerous reasons other than an intent to avoid prosecution. While several studies have shown success in reducing FTA rates through interventions such as clarifying court forms and reminding defendants of appearance dates and times, there are no studies addressing a defendant’s lack of transportation to the courthouse. However, researchers have demonstrated success in reducing missed medical appointments by offering free transportation; ironically, it may be that the offer of free transportation, not the use thereof, is enough to reduce missed appointments. This study tests the hypothesis that the offer of free transportation through a popular rideshare app will reduce the FTA rate in criminal proceedings in the Cambridge and Malden Courthouse.
External Link(s)
Registration Citation
Greiner, Daniel James and Matthew Stubenberg. 2020. "Ride Sharing App FTA Study." AEA RCT Registry. November 23. https://doi.org/10.1257/rct.6738-1.2000000000000002.
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Experimental Details
This study tests the hypothesis that the offer of free transportation through a popular rideshare app will reduce the failure to appear rate in criminal proceedings in the Cambridge and Malden Courthouse located in Massachusetts. The study will be a randomized controlled trial. This is a pilot study to determine the feasibility of a larger study.
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
Failure to appear rate at all court hearings for participants for six months after arraignment.
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
- Length of time a case takes to disposition.
- Disposition of the participants case.
- Length of probation and length of incarceration at the time of disposition.
- Distance from courthouse compared to FTA rate.
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
Participants will be defendants who have a criminal case in the Cambridge or Malden courthouse (Massachusetts), live in one of the surrounding cities (see list below), and meet the eligibility criteria below.

All criminal defendants must go to Probation Service Department before their arraignment. Here defendants will be screened and those who meet the criteria below will be asked to return to Probation Services after arraignment. Those who did not have their case dismissed at arraignment and return to Probation Services will be asked to participate in the study and sign a consent form.

The treatment group will be given an index card with instructions and a phone number to call on the morning of any court hearing in the first six months. They will be told they have two free rides that can be used for any of their criminal case’s court appearances for the first six months of their case starting from their arraignment date. They can call that number on the morning of their hearing and a Probation Services staff member will book them a ride from their house to the Court and after the hearing, either back to their house or to their job if it is located in one of the cities listed below. Defendants who work outside the approved list of cities can be provided with a ride from the Court to a public transportation stop in one of the approved cities. The control group will be told simply to make sure to attend their court hearings.

Probation Services staff will answer calls from the treatment group participants the morning of their court hearing (if they choose to call). The staff member will order a ride for the participant using the rideshare app's online portal. It should be noted this is different from the normal rideshare app usage where a person would order the ride through the app on their phone. The participant does not need to have the rideshare app installed on their phone as any messages from the driver will be relayed to the participant via text message.

Probation Services staff are present in the Courtroom and will record whether a participant is present or not for their court hearing.

Eligibility Criteria:
- Over the age of 18
- English speaker
- Currently a defendant in a criminal case in Cambridge District Court or Malden District Court
- Lives in one of the cities listed below
- Does not have access to a car
- Is not represented by private counsel
- Is determined to be indigent
- Reports to the Probation Services Department after their arraignment
- Not incarcerated while they await trial
- Has a cell phone
- The case does not contain a domestic violence charge

- Cambridge
- Somerville
- Everett
- Revere
- Malden
- Medford
- Arlington
- Belmont
- Watertown
- Winchester
- Stoneham
- Wakefield
- Melrose
- Saugus
- Chelsea
Experimental Design Details
Not available
Randomization Method
Randomization will be done by block randomization in blocks of 20 with 10 treatment and 10 control in each block ordered randomly.
Randomization Unit
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
Sample size: planned number of observations
800 individuals
Sample size (or number of clusters) by treatment arms
400 control group
400 treatment group
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
The minimum detectable effect size for this study is 6%. This calculation is based on an average FTA rate of 17% and a total enrollment of 800 participants. While the primary purpose of the study is to determine the viability of a field operation and produce literature to fill the void of legal based transportation RCTs, it might still be possible to detect a statistically significant change within the proposed enrollment. The literature shows between 24% and 51% of people identified transportation as a barrier in getting to their medical appointments. If the relationship between the medical field and legal field is similar and the consequence of incarceration pushes more people to take advantage of the free ride, it may be possible to observe a 34% drop or 6 percentage point drop in the FTA rate. For a full study we would recommend a minimum detectable effect size of between 3.4% and 4.25% which would represent a drop in the FTA rate of 20%-25%. In order to achieve this minimum detectable effect size we would need approximately 2250 participants in the study.
IRB Name
Harvard University-Area Committee on the Use of Human Subjects
IRB Approval Date
IRB Approval Number
Analysis Plan
Analysis Plan Documents

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Uploaded At: November 23, 2020